I'm renovating an old house, i.e. no straight angles!

Now I'm about to tackle this vertical corner with drywall. However, the top requires some shims, about an inch, in order to line up with existing drywall, while the bottom does almost match up.

I'm thinking of creating a long shim from a 2x4, going from the floor all the way up, but perhaps there is a better way?

Top of tricky corner

Bottom of tricky corner!

  • 1
    A table saw and ripped material to thickness would good here. If you have a tablesaw, I can elaborate in an answer Even a circular saw will work.
    – Jack
    Feb 7 at 15:00

2 Answers 2


The trick here is getting to an outcome that's not just right for very localized points, but for the overall situation. You want straight and square to the extent possible. You want to ease any oddness out over a distance, not suddenly. You want it to look right when you're done, even if it's not geometrically correct.

I would start with a carpenter's string line. Attach it to nails set at the wall corner. Using long straightedges laid horizontally on the walls, set its position at the ceiling and the floor with respect to both wall planes. Make adjustments until you have a good compromise so that both wall planes end up acceptably flat and the door opening isn't severely affected.

Now assess. I like to use long, solid shims for this so you don't end up wavy or lumpy. You can fix some of that with your corner bead, but it's better to get close with the actual drywall. At say 12" (25cm) intervals, measure the gap between framing and the string. Deduct your drywall panel thickness and the depth of the corner bead and there's your shim thickness at that point. Transfer those to your lumber, draw lines between, and cut it out. Put the cut edge to the wall as the factory edge will be relatively straight. Set its position so that it's also correct for the second wall plane.

You may want to do this twice--once at the corner and once at the door framing. This gives your drywall two stable points of contact.


Use cut chunks of drywall for shims, but short of the intended finished surface level. Then a layer of hot mud to flatten everything. Tape the drywall transitions to the hot mud like you would tape a joint between two sheets of drywall.

  • That makes sense. So, do I splat the hot mud directly onto the wood? Feb 6 at 19:57
  • @Totte, you mean for evenness with that door casing? Use drywall beside it. I would replace the door casing. As a hack, I might plane the casing flush to the framing and lap the drywall over it with J-bead framing the opening. You should search for questions on short casings, where you'll probably find better advice.
    – popham
    Feb 6 at 20:16

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